This invention relates in general to vehicle disc brake assemblies and in particular to an improved structure for a slide pin bushing and boot seal assembly adapted for use in such a vehicle disc brake assembly.
Most vehicles are equipped with a brake system for retarding or stopping movement of the vehicle in a controlled manner. A typical brake system for an automobile or light truck includes a disc brake assembly for each of the front wheels and either a drum brake assembly or a disc brake assembly for each of the rear wheels. The brake assemblies are actuated by hydraulic or pneumatic pressure generated when an operator of the vehicle depresses a brake pedal. The structures of these drum brake assemblies and disc brake assemblies, as well as the actuators therefor, are well known in the art.
A typical disc brake assembly includes a rotor which is secured to the wheel of the vehicle for rotation therewith. A caliper assembly is slidably supported by pins secured to an anchor plate. The anchor plate is secured to a non-rotatable component of the vehicle, such as the vehicle frame. The caliper assembly includes a pair of brake shoes which are disposed on opposite sides of the rotor. The brake shoes are operatively connected to one or more hydraulically actuated pistons for movement between a non-braking position, wherein they are spaced apart from opposed braking surfaces of the rotor, and a braking position, wherein they are moved into frictional engagement with the opposed braking surfaces of the rotor. When the operator of the vehicle depresses the brake pedal, the piston urges the brake shoes from the non-braking position to the braking position so as to frictionally engage the opposed braking surfaces of the rotor and thereby slow or stop the rotation of the associated wheel of the vehicle.
As mentioned above, the caliper assembly is slidably supported by pins secured to the anchor plate. A typical pin includes a non-threaded main body and threaded end. The main body of the pin extends into a non-threaded aperture formed in the anchor plate, and the threaded end of the pin is received in threaded opening provided in the caliper assembly. Since the pins slidably support the caliper assembly relative to the anchor plate, it is important that the caliper assembly is sufficiently supported by the pins while still being able to freely slide. It is known to insert a pin bushing in the aperture of the anchor plate to provide the associated pin with a smooth sliding surface. Also, it is known to install a boot seal on the pin to cover the aperture and therefore, protect the smooth sliding surface from debris. U.S. Pat. No. 5,358,079 to Brown, U.S. Pat. No. 5,183,136 to Maeda et al., U.S. Pat. No. 4,962,979 to Odaka, U.S. Pat. No. 4,308,938 to Denton, U.S. Pat. No. 4,753,326 to Weiler et al., U.S. Pat. No. 4,401,194 to Klassen, U.S. Pat. No. 4,331,221 to Evans, and U.S. Pat. No. 4,265,340 to Scott et al. disclose known slide pin bushing and/or boot seal structures.